Filamentary silver suspensions and elements containing same

ABSTRACT

This invention relates to photographic elements having at least one layer which contains a filamentary silver suspension and to processes of heating elements containing said suspensions to change the adsorption characteristics thereof. Elements containing uniform coverage layers of filamentary suspensions can be heated to temperatures of at least 150* C. to reduce the light adsorption over at least one third of the visible light spectrum. Antihalation layers for heat-processable elements can be provided by utilization of the filamentary silver suspension in said elements.

Bacon 1 Mar. 21, 1972 FILAMENTARY SILVER SUSPENSIONS AND ELEMENTS CONTAINING SAME [72] Inventor: Robert Elwin Bacon, Rochester, [73] Assignee: Eastman Kodak Company, Rochester,

[22] Filed: Sept. 29, 1969 [21] Appl. No; 861,584

[52] U.S. Cl ..96/84, 96/107, 96/108 [51] Int. Cl ..G03c H84 [58] Field ofSearch ..96/84, 107, 108; 106/1 [56] References Cited UNITED STATES PATENTS 2,688,601 9/1954 Herz ..96/84 3,053,655 9/1962 Dreyfuss et a1. ..96/73 3,144,332 4/1964 Brown et al..... ..96/107 3,333,960 8/1967 Posse et a1. 96/84 3,392,021 7/1968 McGuckin... 96/84 3,418,122 12/1968 Colt ..96/63 3,447,927 6/1969 Bacon et a1. 96/108 3,459,563 8/1969 Terashima et 211. ....96/84 3,511,660 5/1970 Stevens et a1. ..96/84 /.0 ELEMENTS BEFORE HEA TING OTHER PUBLICATIONS Mees et al., The Theory of the Photographic Process," The Macmillan Co., N.Y., 1966, pp. 340 & 341

Skillman et al., Effect of Particle Shape on the Spectral Absorption of Colloidal Silver in Gelatin" The Journal of Chemical Physics, Vol.48, No. 7, Apr. 1968, pp. 3297- 3304 James, The Stability of Silver Filaments," Photographic Science & Engineering, Vol. 9, No. 2, Man-Apr. 1965, pp. 121 132 Primary Examiner.lohn T. Goolkasian Assistant Examiner-D. J. Fritsch ArtorneyW. H. J. Kline, B. D. Wiese and Gerald E. Battist [57] ABSTRACT This invention relates to photographic elements having at least one layer which contains a filamentary silver suspension and to processes of heating elements containing said suspensions to change the adsorption characteristics thereof. Elements containing uniform coverage layers of filamentary suspensions can be heated to temperatures of at least 150 C. to reduce the light adsorption over at least one third of the visible light spectrum. Antihalation layers for heatprocessable elements can be provided by utilization of the filamentary silver suspension in said elements.

9 Claims, 2 Drawing Figures F/LAM/NTAR) SILVER SUSPENSION AND CON 7A lN/N G SAME AFTER HEAT/N6 5" AT 235% WAVELENGTH (MILL/MICRONS} Patented OPT/CAL DENSITY March 21, 1972 FIG.

F/LAM/NTAR) SILVER SUSPENSION AND /.0 ELEMENTS CONTAIN/N6 SAME x a 30.8 AFTER HEAT/N6 5" AT 235% a a 0.6 E g 0.4

0.2 BEFORE HEAT/N6 WAVELENGTH (MILL/MICRONS) FIG. 2

AFTER HEAT/N6 5 AT 235% BEFORE HEAT/N6 WAVELENGTH (MILL/MICRONS) ROBER T E. BA 001v 1N VEN'IUR.

BY \zwg xyrg/ A 7'TORNE) FILAMENTARY SILVER SUSPENSIONS AND ELEMENTS CONTAINING SAME This invention relates to photographic elements containing layers of a filamentary silver suspension. In one aspect, this invention relates to photographic elements containing an antihalation layer which comprises a filamentary silver suspension. In another aspect, this invention relates to a process of heating photographic elements containing a layer containing a uniform filamentary silver suspension to change the spectral absorption properties of the silver suspension. In still another aspect, this invention relates to heat-processable photographic elements containing antihalation layers.

It is known in the art to use yellow colloidal silver dispersions as antihalation layers or filter layers in combination with blue-sensitive emulsions. When using panchromatically sensitized emulsions, the antihalation layer must absorb in the entire region of sensitivity if it is to be an effective antihalation layer. Mixtures of silver sols, such as disclosed in U.S. Pat. No. 3,333,960, and blueor gray-colored dispersions of silver, such as disclosed in Herz, U.S. Pat. No. 2,688,601, disclose effective materials for extended absorption of panchromatically sensitized film. These antihalation materials are quite effective for developing-out photographic materials as the colloidal silver can be chemically bleached out in the color processing.

It is now desirable to provide filter layers and/or antihalation layers for photographic elements which are not necessarily subject to photographic fixing baths wherein they can be removed.

1 have now discovered new silver materials and combinations containing suspensions of silver that can be effectively used as an antihalation layer for panchromatically sensitive photographic elements which do not require removal by bleach or fixing techniques. In one preferred embodiment, suspensions of silver according to this invention can be heated at temperatures of 200 C. or above wherein they change color or there is at least a percent and preferably a 50 percent reduction in density over at least one third of the visible light spectrum. In those instances where the image areas are gray or black, a reduction in density over at least one third of the spectrum will provide highly improved appearance of the image record even if the remainder of the absorption properties of the layer are increased.

In one preferred embodiment of this invention, the silver is a filamentary silver which can be converted to a spherical silver having different absorption characteristics by heating to at least 180 C.

In another preferred embodiment, the filamentary silver layer comprises a green or red absorbing dye.

In another embodiment, a layer comprising filamentary silver is used in combination with a layer of a printout silver salt emulsion and preferably in combination with a silver halide composition comprising silver halide grains having polyvalent metal ions occluded therein and a halogen acceptor contiguous to said grains.

in still another embodiment, this invention relates to directprint elements comprising at least one layer containing filamentary silver.

In still another embodiment, filamentary silver dispersions having absorption primarily in the blue area of the spectrum can be combined with organic dyes having absorption in the red and/or green areas of the light spectrum depending on the sensitivity of the light-sensitive silver halide material used in combination therewith. The dye can then be treated with an acid solution or basic solution to change the adsorption characteristics of the layer reducing light adsorption in the green or red region respectively.

It is known in the art that filamentary silver suspensions can be prepared such as disclosed in Mees and James, The Theory of the Photographic Process, 1966, pages 340-341, and Skillman and Berry, The Journal of Chemical Physics, Vol. 48, No. 7, pages 3297-3304, Apr. 1, 1968. Moreover, it is known that the silver filaments can be converted to silver spheres in hot aqueous KCL solutions or thiocyanate solutions as disclosed by James, Photographic Science and Engineering, Vol. 9, No. 2 March-April, 1969, pages 121-132. However, it was quite unexpected to find that layers of filamentary silver dispersions would provide good antihalation layers in heatprocessable photographic elements wherein heat was used to process the elements; the spectral absorption of the antihalation sufficiently changed over at least a portion of the visible spectrum to obviate the necessity of removing the silver antihalation layer with liquid solvents.

The filamentary grains can be heated to temperatures of at least above C. in a dry process to convert them to spherical-shaped particles with a change in light absorption. The preferred dry-process temperature range is from about C. to about 250 C.

Several techniques can be used to supply the necessary heat to the layers containing the filamentary silver. One technique which has proven quite satisfactory is contact with a hot platen similar to that disclosed in U.S. Pat. No. 3,144,332. Where it is desirable to provide heat without contact with the photographic element, other methods of heat transfer can be used which have also been found very useful for heating heatprocessable emulsions, as disclosed in Colt, U.S. Pat. No. 3,418,122, and Bacon and Barbier, U.S. Pat. No. 3,447,927 issued June 3, 1969. Typical useful methods of this type include the use of an infrared heater such as, for example, a heated stainless steel bar optionally used in combination with a reflector if a transparent element is being heated; the use of hot air; or the use of lasers such as, for example, C0 continuous-wave lasers as disclosed by Ray A. Paananen, Progress in Ionized- Argon Lasers, IEEE Spectrum, Vol. 3, page 88, June 1966.

The filamentary silver layer can also be rapidly cooled after heating, if desired, by means found useful in processing the emulsions ofColt and Bacon et a1. above such as, for example, by contact with thermoelectrically cooled surfaces at temperatures of around 0 C. for short time periods.

The filamentary silver of this invention is prepared by developing light-exposed or chemically fogged fine-grain silver halides. Generally, the silver halides have an average size of less than 700 A. and preferably less than about 500 A. If the grains are too large, they do not form the desired filamentary structure according to the invention. The silver halide grains are preferably silver bromide, silver chloride or mixtures thereof, and preferably are made by such techniques which produce uniform-size distributions of grains. Typical methods of this type include the growth of grains in the presence of heterocyclic mercaptans, such as disclosed in Berry and Skillman, U.S. Ser. No. 617,818 filed Feb. 23, 1967, now abandoned. Preferred heterocyclic mercaptans include the aryl mercaptotetrazoles such as dicarboxy-l-phenyl-S- mercaptotetrazole and the like.

The fine-grain silver halides are fogged by light exposure or a chemical fogging agent. Typical useful chemical fogging agents include stannous salts, such as described in Carroll, U.S. Pat. No. 2,487,850, formamidene sulfinic acid such as described in Allen et al., U.S. Pat. No. 2,983,609, and the like. Generally, sufficient light or reducing agent is used to make each grain developable in the silver halide developer.

The fogged silver halide grains are then subjected to development in a developing solution. Preferably this solution is substantially free of all strong silver halide solvents such as alkali metal thiocyanates, thiosulfates and the like. Typical useful reducing agents useful in the developing solution include hydroquinones, catechols, aminophenols, 3- pyrazolidones, ascorbic acid, reductones, phenylamines and the like. The development is carried out at temperatures which will produce an axial ratio of 2:] of the filamentary silver and preferably 4:1. The fogging and/or development of the silver halide can occur before or after coating of the silver halide on a support. At least 70 percent of the filamentary grains, when viewed in photomicrographs, have a length-towidth ratio of at least 2 and preferably at least 4 when using the averaged width of each width dimension. The filamentary grains of this invention are quite distinct from the commonly used yellow colloidal silver which comprises spherical grains of silver.

The filamentary silver suspensions are generally used as a uniformly dispersed layer in a photographic element. Typical photographic heat-processable elements, i.e., those which do not require application of external liquid developing agents, are printout elements as disclosed in Bacon et al., U.S. Pat. No. 3,447,927 issued June 3,1969, dry physical development elements such as disclosed in U.S. Pat. No. 3,457,075 issued July 22,1969, photothermographic elements such as disclosed in U.S. Pat. No. 3,392,020 issued July 9,1968, direct-print elements as disclosed in McBride, U.S. Pat. No. 3,287,137 issued Nov. 22,1966, and incorporated developer elements as disclosed in U.S. Pat. No. 3,312,550 issued Apr. 4, 1967. Of course, the layers are especially useful in systems where heat is applied in the development or stabilization of the photosensitive layer of the photographic element. Generally, the filamentary silver suspension is coated at a coverage of about 10 to about 10 moles per square foot and preferably 10' to about moles per square foot.

Preferred silver halide recording layers which are useful in elements made in accordance with this invention comprise silver halide grains having polyvalent metal ions or atoms occluded therein. The silver halide grains having occluded polyvalent metal ions therein are generally obtained by precipitating in the presence of the polyvalent metal ions and preferably in an acid medium. Typical emulsions of this type are disclosed in U.S. Pat. No. 3,447,927 issued June 3,1969, and in Bacon, U.S. Ser. No. 629,090 filed Apr. 7, 1967. These emulsions are useful in recording electromagnetic radiation such as electrons, light, X-rays etc. In certain preferred embodiments of this invention, the emulsion contains silver halide grains with trivalent metal ions occluded therein.

Typical silver halide compositions mentioned above contain a halogen acceptor which is generally contiguous with the silver halide grains in the system. Generally, suitable halogen acceptors are compounds which enhance the photolytic yield (as determined by radiographic analysis, for example) and/or the photolytic density ofa printout emulsion.

The above-described emulsions and filamentary silver layers can be coated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include glass, metals, paper, polyethylene-coated paper, polypropylene-coated paper, cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethyleneterephthalate film and related films of resinous materials and others. In one preferred embodiment wherein high temperatures can be used to process the elements of this invention, film supports are utilized which have a heat distortion temperature of at least 160 C. and more preferably of at least 180 C. in both the length and width directions of the support; heat distortion temperature can be calculated according to ASTM-D-l637-61. Typical preferred supports of this embodiment are heat-set polyesters, for example, polyethylene terephthalates, cyclohexylenedimethylene terephthalates, etc.; high-temperature polyimides, heat-resistant polycarbonates, and related film supports having high heat distortion temperatures.

In one preferred embodiment, photographic elements comprising a filamentary silver layer according to the present invention and at least one layer comprising silver halide grains having polyvalent ions occluded therein provide good image records with improved image properties, acceptable background color and high background stability when exposed to light for prolonged periods of time. A suitable lightdevelopment process is disclosed in Colt, U.S. Pat. No. 3,418,122 issued Dec. 24, 1968. In such a photodevelopment application, the silver halide coating is imagewise exposed to form a latent image, the exposed coating is heated to at least about 300 F., and after heating the coating is uniformly exposed to light for a time sufficient to produce a visible image. The heating step in such a photodevelopment process represses the usual printing out of unexposed or non-image areas (Dmin), the original recording sensitivity of the silver halide being inactivated by such heating. Images thus prepared have a high degree of permanence or stability to ambient light. Moreover, the filamentary silver will be converted to a spherical colloidal silver having lower adsorption in the green and red regions of the spectrum.

The organic dyes which can generally be used in combination with the filamentary silver according to certain embodiments of this invention include those which can be reduced in green or red adsorption by at least 50 percent upon contact with a simple acid or base solution. Typical useful dyes include azo dyes such as described in Gasper, U.S. Pat. No. 2,688,542 and U.S. Pat. No. 3,053,655.

The invention can be further illustrated by the following examples of preferred embodiments thereof, although it will be understood that the examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise indicated.

EXAMPLE 1 Preparation of a filamentary silver suspension A precipitation of silver bromide particles with a size range of from less than A. to about 350 A. diameter, average of 225 A., is produced by double-jet addition of 61.7 ml. 1.0 m. AgNo and 61.1 ml. 1.0 m. KBr into 300 ml. of an aqueous solution of 10 g. gelatin and 0.6 g. dicarboxy phenyl mercaptotetrazole at 32.5 i- 1.3"v C. over a 30-minute period. This is chilled, set, noodled and washed 1 hour with 5 C. water. This is sulfur-sensitized by addition of0.021 mol sodium thiosulfate per mol of silver bromide to the melted emulsion and holding at 40 C. for 4 hours. This is coated on acetate film base by hand with a coating knife to give 0.006-inch thickness. After coating, portions of the element are exposed to a single flash from a General Electric FT-217 flash tube at a distance of 8 inches. The samples are developed in Kodak Developer D-8 at 20 C. for 20 seconds, fixed in Kodak Fixer F-5 for 2 minutes, washed and dried. The absorption spectra for this layer are substantially uniform over the range of 400 millimicrons through 800 millimicrons. The layer contains filamentary silver having an average axial ratio of greater than 3:1.

EXAMPLE 2 A neutral-colored filamentary-grain silver dispersion is prepared as follows:

To 40 g. ofa gelatin dispersed in 1,972 ml. ofwater containing 4 g. of potassium bromide is added simultaneously the following two solutions over a period of 4 minutes at 100 F.: (1) 169.9 g. of silver nitrate dissolved in 434 ml. of water and (2) 59.7 g. of potassium bromide and 308 g. of sodium chloride dissolved in 434 m1. of water. The temperature is then increased to F. and the following four parts added:

1. 0.33 g. of stannous chloride dissolved in 0.33 ml. of

hydrochloric acid to total volume of31.4 ml. ofwater;

2. 1.36 g. of 2mercaptobenzothiazole in 129 ml. of methyl alcohol;

3. the following solution is added in 20 seconds:

85.5 g. ofsodium sulfite,

515.0 m1. ofwater,

61.5 g. of hydroquinone,

1710 ml. ION sodium hydroxide;

4. 259 g. of sodium sulfate.

The above mixture is then coagulation-washed three times by the procedure described in Yutzy et al., U.S. Pat. No. 2,614,968. The resulting coagulum is then dispersed in 2,590 ml. of water and g. of a gelatin for 15 minutes at 130 F. and a pH 6.0. The silver filaments of this mixture have an average edge length of 0.02 micron and an average axial ratio of 5: 1.

The above dispersion wherein the reducing agent is added to a low-gelatin dilute silver salt solution is similar to the procedure described in The Chemistry of Colloids, by Zsigmondy and Spear, Wiley, New York, 1917.

EXAMPLE 3 A blue-colored silver dispersion according to the prior art is prepared as described in Example 1 of Herz, U.S. Pat. No.

2,688,601. This dispersion is then coated at 1.0 mg. silver/ft. on a film support. The coated support is then heated to 235 C. for 5 seconds.

The transmittance curves for this suspension before heating and after heating are shown in FIG. 2.

EXAMPLE 4 A neutral-colored silver dispersion is prepared as described in Example 2, coated on a support at 1 mg. of silver/ft. and then heated to 235 C. for 5 seconds.

The transmittance curves for this emulsion before heating and after heating are shown in FIG. 1. Photomicrographs magnified 60,000 times illustrate that the neutral-colored silver dispersion which as a filamentary form before heating changes to a spherical form after heating while the non-neutral-colored dispersion which has a spherical form before heating remains in essentially the same spherical form after heating.

EXAMPLE 5-A A control coating of the type described in Example 18 of Bacon et al., U.S. Pat. No. 3,447,927 issued June 3, 1969, is prepared, coated on a heat-resistant film support at 280 mg. Ag/ftF, processed and photodeveloped as described in Example 18 of said Bacon patent.

EXAMPLE 5B An emulsion is prepared as in Example 5-A and coated at 280 mg. Ag/ft. over a silver dispersion prepared according to Example 2 that has been coated on a heat-resistant film support at about 3 mg. Ag/fti". The coating is processed as described in Example 5-A. The best results are obtained when the silver dispersion is coated to give a blue-absorption density of at least 0.1 and preferably 0.3 to 1.0. The coating retains a yellow coloration after heat treatment, which is not unfavorable since it increases apparent maximum density.

The image record in the above photographic elements is much sharper and distinct than the corresponding image record in the control coating of Example 5A.

Similar improved results are obtained when layers containing filamentary silver suspensions are used in photographic elements under dry physical development layers, photothermographic layers and direct-print layers. Similar results are also obtained when the coating of Example 1 is utilized in combination with the emulsion of Example 5A.

EXAMPLE 6 An emulsion is prepared as in Example 5-A above and spectrally sensitized with a merocyanine green-sensitizing dye. The spectrally sensitized emulsion is then coated at 280 mg. Ag/ft. over a neutral-colored filamentary-grain silver dispersion that is coated at about 1 mg. Ag/ft. on a heat-resistant film suport. p After processing as described in Example 5-A, the samples revert to a yellow appearance similar to those obtained in Example 5-B.

EXAMPLE 7 A spectrally sensitized emulsion as in Example 6 is coated at 280 mg. Ag/ft. over a silver dispersion containing a green-absorbing dye, known as ethyl red, that produces a reddishbrown coating over-all coloration. The absorbing layer is coated at about 3 mg. Ag/ft. on a heat-resistant film support with processing performed as in previous examples. The result exhibits improved sharpness with no alteration in the original reddish-brown coloration as a result of heating.

The green absorption of the ethyl red absorbing dye used in this example may be reduced to obtain a more desirable tone by acidifying the layer.

Visual comparison of the samples in Examples 5-B, 6 and 7 with the control (Example 5A) clearly indicates that image sharpness is substantially improved.

Similar results are obtained when nickel dimethyl glyoxime, 8-hydroxy quinoline vanadium complex as disclosed in U.S. Pat. No. 3,364,029, quinhydrones such as disclosed in U.S. Pat. No. 2,899,334, the aluminum lake of aurin tricarboxylic acid and pentadiene dianiline hydrochloride are used in combination with the filamentary silver in an antihalation la er.

Although the invention has been described in consi erable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention.

lclaim:

l. A heat-proc'essable photographic element comprising 1 a support, 2) at least one layer comprising silver halide grains having polyvalent metal ions occluded therein and a halogen acceptor contiguous to said grains and 3) at least one layer containing a uniform coverage of a filamentary silver suspension.

2. A photographic element according to claim 1 wherein said filamentary silver has an average length-to-width ratio of 4:1.

3. A heat-processable printout photographic element comprising l) a support, 2) at least one layer comprising a radiation-sensitive printout composition and 3) a layer comprising a filamentary silver suspension.

4. A photographic element according to claim 3 wherein said filamentary silver layer comprises a uniform coverage dispersion of said filamentary silver suspension at a coverage of about 10' moles to about 10 moles per square foot.

5. A photographic element according to claim 3 wherein said filamentary silver suspension consists of silver filaments having an axial ratio of at least 2:1.

6. A photographic element according to claim 3 wherein there is at least a 20 percent reduction in density in said filamentary silver layer over at least one third of the visible light spectrum when said element is heated to at least C.

7. A printout photographic element according to claim 3 wherein said radiation-sensitive layer comprises silver halide grains having trivalent metal ions occluded therein.

8. A printout photographic element according to claim 3 wherein said filamentary colloidal silver comprises at least 70 percent, by number, of grains having a length-to-width ratio of at least 4.

9. A heat-processable printout photographic element comprising l) a support, 2) at least one layer comprising a radiation-sensitive printout composition and 3) at least one layer comprising the combination of a colloidal filamentary silver and an organic adsorbing dye wherein said combination has an effective light adsorption over the entire range of radiation sensitivity of said radiation-sensitive composition.

mgr UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 5 ,753 Dated" March 21, 1972 Inventor(s) RObOIt E. Bacon It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

a- *1 In column 1, line 16 (page 1, line IL of the application) "absorb" should read ---adsorb---.

In column 1, line 21 (page 1, line 19 of the application), "absorption" should read -adsorption-- In column 1, line L l (page l,' line 8 of the application), "absorption" should read adsorption--.

In column 1, line L E (page 1, line 12 of the application) "absorption" should read -adsorption--- In column 1, line LIB (page 1, line 15 of the application) "absorption" should read ---ads orption In column 1, line 59 (page 1, line 26 of the application) "absorption" should read -adsorption--- In column 1, line 60 (page 1, line 27 of the application), "absorption" should read --adsorption---.

In column 1, line 73 (page 2, line 9 of the application) "KCL" should read --KCl--.

In column 2, line 28 (page Lt, line 5 of the application), "C0 should read --GO Signed and sealed this 5th day of September 1972.

(SEAL) L Attest J EDWARD M .FLETCHERQJR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

2. A photographic element according to claim 1 wherein said filamentary silver has an average length-to-width ratio of 4:1.
 3. A heat-processable printout photographic element comprising 1) a support, 2) at least one layer comprising a radiation-sensitive printout composition and 3) a layer comprising a filamentary silver suspension.
 4. A photographic element according to claim 3 wherein said filamentary silver layer comprises a uniform coverage dispersion of said filamentary silver suspension at a coverage of about 10 5 moles to about 10 4 moles per square foot.
 5. A photographic element according to claim 3 wherein said filamentary silver suspension consists of silver filaments having an axial ratio of at least 2:1.
 6. A photographic element according to claim 3 wherein there is at least a 20 percent reduction in density in said filamentary silver layer over at least one third of the visible light spectrum when said element is heated to at least 180* C.
 7. A printout photographic element according to claim 3 wherein said radiation-sensitive layer comprises silver halide grains having trivalent metal ions occluded therein.
 8. A printout photographic element according to claim 3 wherein said filamentary colloidal silver comprises at least 70 percent, by number, of grains having a length-to-width ratio of at least
 4. 9. A heat-processable printout photographic element comprising 1) a support, 2) at least one layer comprising a radiation-sensitive printout composition and 3) at least one layer comprising the combination of a colloidal filamentary silver and an organic adsorbing dye wherein said combination has an effective light adsorption over the entire range of radiation sensitivity of said radiation-sensitive composition. 